Yes I understand the difference between client-side and server-side. Examples I've found say something about hidden fields in a form and posting, just not clear enough for me. this is what I am shooting for. when the page loads, it loads the correct background image based on client resolution. the variable is a simple screen.width, no problem. What I am stuck on is this: I need that screen.width variable to be passed on to PHP in the same page. I am trying to use <?php include (filename); ?> based on that screen.width variable. I.E. <?php $var = screen.width variable passed from javascrip
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On the index page compute the browser variables and based on this information redirect the user to appropriate page Orstore the browser variables into the session on first page and then call another page which. On second page you can include appropriate files based on the session information.

You can communicate the server side and client side only by making a request or post, they don't (can't) know each other on the client side. Most used technique is to post some hidden vars to server side to make the server side know that the client has those vars.